The present invention generally relates to appliances having a plurality of user actuated keys. More particularly, the present invention relates to a keypad for such devices.
Multiple key keypads are used to control many types of appliances. For instance, keypads are commonly found on microwaves, telephones, remote controls and computer input devices, such as keyboards, mice and other gaming devices, to name a few. Current keypad technology generally utilizes electrical signals to detect keystrokes. For example, many keypads have conductive membranes to detect key actuation. The membrane includes conductive traces or circuits, which must remain electrically isolated from one another in order to operate correctly. The requirement of electrical isolation complicates the keypad design particularly when many keys are present.
In addition, current keypad or keyboard technology limits detection of simultaneously actuated keys. For example, almost all computer keyboards detect actuation of the xe2x80x9cshiftxe2x80x9d key and any other alphanumeric key in order to provide capital letters or other special characters. Likewise, computer keyboards also detect simultaneous actuation of the xe2x80x9ccontrolxe2x80x9d or xe2x80x9caltxe2x80x9d keys in combination with other keys. However, keyboards generally do not detect simultaneous actuation of any combination of keys. This is due in part to electric circuit density limitations and the necessity for electrical isolation between adjacent circuits in a planar structure. Nevertheless, detection of other key combinations can be advantageous, for instance, in developing character based icons with a keyboard, as found, for example, with Japanese language icons.
Apart from the increased functionality of detecting other combinations of simultaneously actuated keys, there is a separate desire to reduce costs and complexity of current keypads and keyboards. An improved keypad or keyboard that addresses one, some or all these concerns is therefore desired.
A first broad aspect includes a keypad having a light emitting source, a light detector and waveguide assembly adapted to receive light from the light emitting source and having a plurality of waveguide branches is adapted to conduct light to the light detector. A plurality of user actuated keys is provided. Each key includes a moveable engaging member disposed proximate a waveguide branch to engage the waveguide branch as a function of key operation.
A second broad aspect is a method of forming a waveguide assembly having a plurality of waveguide branches. The method includes providing a waveguide medium capable of conducting light; and inducing stress in the waveguide medium to define light conducting waveguide branches.